1. Field of the Invention
The invention relates to a power amplifier, and more particularly to a power amplifier, which is capable of avoiding a short through current.
2. Description of the Related Art
Highly efficient audio amplifiers are very important in mobile products. In electronic devices with high power respect the audio amplifiers. When the power of the audio amplifiers becomes large, the efficiency of the audio amplifiers becomes important. Power amplifiers comprise class A amplifiers, class B amplifiers, class C amplifiers, and class AB amplifiers according to different work points.
When a class A amplifier does not receive an input signal, current is continuously provided from an output terminal thereof. Thus, efficiency of the class A amplifier is lower than a class B amplifier, a class C amplifier, and a class AB amplifier. When a class B amplifier receives an input signal, the class B amplifier operates in a half-cycle of the input signal. In other words, when the class B amplifier does not receive an input signal, no current is provided from the output terminal of the class B amplifier. However, the class B amplifier has a crossover distortion issue. A class AB amplifier benefits from the advantages of the class A amplifier and the class B amplifier. The class AB amplifier is capable of eliminating the crossover distortion issue.